Subcutaneous electrode and lead with phoresis based pharmacological agent delivery

ABSTRACT

An implantable subcutaneous device includes a lead and electrode for cardiac monitoring and intervention. The device has an implantable lead including a lead body, a subcutaneous electrode supported by the lead body and a pharmacological agent impelled from the device using phoresis. The pharmacological agent provides a therapeutic treatment to subcutaneous non-intrathoracic tissue. A method of implanting subcutaneous leads involves providing a lead including a lead body, a subcutaneous electrode, and a pharmacological agent and using phoresis to impel the pharmacological agent into subcutaneous non-intrathoracic tissue surrounding the lead.

RELATED APPLICATIONS

[0001] This application claims the benefit of Provisional PatentApplication Serial No. 60/462,272, filed on Apr. 11, 2003, to whichpriority is claimed pursuant to 35 U.S.C. §119(e) and which is herebyincorporated herein by reference.

FIELD OF THE INVENTION

[0002] The present invention relates generally to subcutaneouslyimplantable cardiac cardioverters/defibrillators and monitors, and, moreparticularly, to subcutaneously implantable leads and device componentsthat impel pharmacological agents using phoresis.

BACKGROUND OF THE INVENTION

[0003] Implantable cardiac rhythm management systems have been used asan effective treatment for patients with serious arrhythmias. Thesesystems typically include one or more leads and circuitry to sensesignals from one or more interior and/or exterior surfaces of the heart.Such systems also include circuitry for generating electrical pulsesthat are applied to cardiac tissue at one or more interior and/orexterior surfaces of the heart. For example, leads extending into thepatient's heart are connected to electrodes that contact the myocardiumfor sensing the heart's electrical signals and for delivering pulses tothe heart in accordance with various therapies for treating arrhythmias.

[0004] Typical implantable cardioverter/defibrillators (ICDs) includeone or more endocardial leads to which at least one defibrillationelectrode is connected. Such ICDs are capable of delivering high-energyshocks to the heart, interrupting a ventricular tachyarrythmia orventricular fibrillation, and allowing the heart to resume normal sinusrhythm. ICDs may also include pacing functionality.

[0005] Although ICDs are effective at preventing Sudden Cardiac Death(SCD), most people at risk of SCD are not provided with implantabledefibrillators. The primary reasons for this unfortunate reality includethe limited number of physicians qualified to perform transvenouslead/electrode implantation, a limited number of surgical facilitiesadequately equipped to accommodate such cardiac procedures, and alimited number of the at-risk patient population that can safely undergothe required endocardial or epicardial lead/electrode implant procedure.Subcutaneous ICDs are being developed to address these and other issues.

SUMMARY OF THE INVENTION

[0006] The present invention is directed to subcutaneous cardiac devicesand components, and methods of using same to improve patient comfort,reduce morbidity, and improve surgical outcomes by incorporatingpharmacological agents that are actively impelled into tissue usingphoresis. According to one embodiment, a cardiac device has animplantable lead including a lead body, a subcutaneous electrodesupported by the lead body, and a pharmacological agent provided on thelead and/or electrode. The pharmacological agent is impelled intosubcutaneous non-intrathoracic tissue using phoresis. In anotherembodiment, an implantable cardioverter/defibrillator system includes acan to which an implantable lead is coupled. One or more pharmacologicalagents may be provided on the lead, electrode, can, or combination ofthese components and impelled phoretically into surrounding tissue.

[0007] An embodiment of the present invention is directed to impelling aplurality of pharmacological agents disposed on a lead and/or anelectrode into tissue using phoresis. Pharmacological agents may beprovided on one or more electrodes alone or in combination withpharmacological agents on the can and/or lead body, all of which areimpelled into surrounding tissue using phoresis.

[0008] A method of implanting subcutaneous leads is directed toproviding a lead including a lead body, a subcutaneous electrode, and apharmacological agent, and delivering the pharmacological agent tosubcutaneous non-intrathoracic tissue using phoresis. The method mayinclude providing a sheath and inserting the lead into the sheath todeliver the lead into subcutaneous non-intrathoracic tissue.

[0009] The above summary of the present invention is not intended todescribe each embodiment or every implementation of the presentinvention. Advantages and attainments, together with a more completeunderstanding of the invention, will become apparent and appreciated byreferring to the following detailed description and claims taken inconjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0010]FIGS. 1A and 1B are views of a transthoracic cardiac sensingand/or stimulation device as implanted in a patient;

[0011]FIG. 2A illustrates a lead in accordance with the presentinvention, inserted in a dissected subcutaneous path extending from thecan;

[0012]FIG. 2B illustrates various components of a transthoracic cardiacsensing and/or stimulation device in accordance with embodiments of thepresent invention;

[0013]FIG. 3 is a plan view of a lead incorporating phoresis baseddelivery of pharmacological agents in accordance with the presentinvention, enclosed within a sheath;

[0014]FIG. 4 is a magnified view of a lead with an electrode configuredto facilitate phoresis based delivery of pharmacological agents inaccordance with the present invention;

[0015]FIG. 5A is a top view of an embodiment of a system configured tofacilitate phoresis based delivery of pharmacological agents inaccordance with the present invention;

[0016]FIG. 5B is a magnified side view of a portion of the canillustrated in FIG. 5A, the can having a polyvinylidene fluoride (PVDF)coating used to facilitate phoresis based delivery of pharmacologicalagents in accordance with the present invention;

[0017]FIG. 6 is a magnified view of an embodiment of a lead configuredto facilitate phoresis based delivery of pharmacological agents inaccordance with the present invention;

[0018]FIG. 7 is a magnified view of another embodiment of a leadconfigured to facilitate phoresis based delivery of pharmacologicalagents in accordance with the present invention; and

[0019]FIG. 8 is a magnified view of another embodiment of a lead with anelectrode configured to facilitate phoresis based delivery ofpharmacological agents in accordance with the present invention.

[0020] While the invention is amenable to various modifications andalternative forms, specifics thereof have been shown by way of examplein the drawings and will be described in detail below. It is to beunderstood, however, that the intention is not to limit the invention tothe particular embodiments described. On the contrary, the invention isintended to cover all modifications, equivalents, and alternativesfalling within the scope of the invention as defined by the appendedclaims.

DETAILED DESCRIPTION OF VARIOUS EMBODIMENTS

[0021] In the following description of the illustrated embodiments,references are made to the accompanying drawings, which form a parthereof, and in which is shown by way of illustration various embodimentsin which the invention may be practiced. It is to be understood thatother embodiments may be utilized, and structural and functional changesmay be made without departing from the scope of the present invention.

[0022] A device employing an implantable lead implemented in accordancewith the present invention may incorporate one or more of the features,structures, methods, or combinations thereof described herein below. Forexample, a subcutaneous cardiac monitor or stimulator may be implementedto include a lead and other components having one or more of theadvantageous features and/or processes described below. It is intendedthat such a device or method need not include all of the features andfunctions described herein, but may be implemented to include selectedfeatures and functions that provide for unique structures and/orfunctionality.

[0023] In general terms, an implantable lead implemented in accordancewith the present invention may be used with a subcutaneous cardiacmonitoring and/or stimulation device. One such device is an implantabletransthoracic cardiac sensing and/or stimulation (ITCS) device that maybe implanted under the skin in the chest region of a patient. The ITCSdevice may, for example, be implanted subcutaneously such that all orselected elements of the device are positioned on the patient's front,back, side, or other body locations suitable for sensing cardiacactivity and delivering cardiac stimulation therapy. It is understoodthat elements of the ITCS device may be located at several differentbody locations, such as in the chest, abdominal, or subclavian regionwith electrode elements respectively positioned at different regionsnear, around, in, or on the heart.

[0024] The primary housing (e.g., the active or non-active can) of theITCS device, for example, may be configured for positioning outside ofthe rib cage at an intercostal or subcostal location, within theabdomen, or in the upper chest region (e.g., subclavian location, suchas above the third rib). In one implementation, one or more electrodesmay be located on the primary housing and/or at other locations about,but not in contact with, the heart, great vessel or coronaryvasculature.

[0025] In another implementation, one or more leads incorporatingelectrodes may be located in direct contact with the heart, great vesselor coronary vasculature, such as via one or more leads implanted by useof conventional transvenous delivery approaches. In anotherimplementation, for example, one or more subcutaneous electrodesubsystems or electrode arrays may be used to sense cardiac activity anddeliver cardiac stimulation energy in an ITCS device configurationemploying an active can or a configuration employing a non-active can.Electrodes may be situated at anterior and/or posterior locationsrelative to the heart.

[0026] Referring now to FIGS. 1A and 1B of the drawings, there is showna configuration of a transthoracic cardiac sensing and/or stimulation(ITCS) device implanted in the chest region of a patient at differentlocations by use of a dissection tool. In the particular configurationshown in FIGS. 1A and 1B, the ITCS device includes a housing 102 withinwhich various cardiac sensing, detection, processing, and energydelivery circuitry may be housed. The housing 102 is typicallyconfigured to include one or more electrodes (e.g., can electrode and/orindifferent electrode). Although the housing 102 is typically configuredas an active can, it is appreciated that a non-active can configurationmay be implemented, in which case at least two electrodes spaced apartfrom the housing 102 are employed. An ITCS system according to thisapproach is distinct from conventional approaches in that it may beconfigured to include a combination of two or more electrode subsystemsthat are implanted subcutaneously.

[0027] In the configuration shown in FIGS. 1A and 1B, a subcutaneouselectrode 104 may be positioned under the skin in the chest region andsituated distal from the housing 102. The subcutaneous and, ifapplicable, housing electrode(s) may be positioned about the heart atvarious locations and orientations, such as at various anterior and/orposterior locations relative to the heart. The subcutaneous electrode104 is electrically coupled to circuitry within the housing 102 via alead assembly 106. One or more conductors (e.g., coils or cables) areprovided within the lead assembly 106 and electrically couple thesubcutaneous electrode 104 with circuitry in the housing 102. One ormore sense, sense/pace or defibrillation electrodes may be situated onthe elongated structure of the electrode support, the housing 102,and/or the distal electrode assembly (shown as subcutaneous electrode104 in the configuration shown in FIGS. 1A and 1B).

[0028] In one configuration, the lead assembly 106 is generallyflexible. In another configuration, the lead assembly 106 is constructedto be somewhat flexible, yet has an elastic, spring, or mechanicalmemory that retains a desired configuration after being shaped ormanipulated by a clinician. For example, the lead assembly 106 mayincorporate a gooseneck or braid system that may be distorted undermanual force to take on a desired shape. In this manner, the leadassembly 106 may be shape-fit to accommodate the unique anatomicalconfiguration of a given patient, and generally retains a customizedshape after implantation. Shaping of the lead assembly 106 according tothis configuration may occur prior to, and during, ITCS deviceimplantation.

[0029] In accordance with a further configuration, the lead assembly 106includes a rigid electrode support assembly, such as a rigid elongatedstructure that positionally stabilizes the subcutaneous electrode 104with respect to the housing 102. In this configuration, the rigidity ofthe elongated structure maintains a desired spacing between thesubcutaneous electrode 104 and the housing 102, and a desiredorientation of the subcutaneous electrode 104/housing 102 relative tothe patient's heart. The elongated structure may be formed from astructural plastic, composite or metallic material, and includes, or iscovered by, a biocompatible material. Appropriate electrical isolationbetween the housing 102 and the subcutaneous electrode 104 is providedin cases where the elongated structure is formed from an electricallyconductive material, such as metal.

[0030] In one configuration, the rigid electrode support assembly andthe housing 102 define a unitary structure (i.e., a singlehousing/unit). The electronic components and electrodeconductors/connectors are disposed within or on the unitary ITCS devicehousing/electrode support assembly. At least two electrodes aresupported on the unitary structure near opposing ends of thehousing/electrode support assembly. The unitary structure may have, forexample, an arcuate or angled shape.

[0031] According to another configuration, the rigid electrode supportassembly defines a physically separable unit relative to the housing102. The rigid electrode support assembly includes mechanical andelectrical couplings that facilitate mating engagement withcorresponding mechanical and electrical couplings of the housing 102.For example, a header block arrangement may be configured to includeboth electrical and mechanical couplings that provide for mechanical andelectrical connections between the rigid electrode support assembly andhousing 102. The header block arrangement may be provided on the housing102 or the rigid electrode support assembly, or both the housing 102 andthe rigid electrode support assembly. Alternatively, amechanical/electrical coupler may be used to establish mechanical andelectrical connections between the rigid electrode support assembly andthe housing 102. In such a configuration, a variety of differentelectrode support assemblies of varying shapes, sizes, and electrodeconfigurations can be made available for physically and electricallyconnecting to a standard ITCS device.

[0032] It is noted that the electrodes and the lead assembly 106 may beconfigured to assume a variety of shapes. For example, the lead assembly106 may have a wedge, chevron, flattened oval, or a ribbon shape, andthe subcutaneous electrode 104 may include a number of spacedelectrodes, such as an array or band of electrodes. Moreover, two ormore subcutaneous electrodes 104 may be mounted to multiple electrodesupport assemblies 106 to achieve a desired spaced relationship amongstthe subcutaneous electrodes 104. Accordingly, subcutaneous leads of thepresent invention may be shaped appropriately for specific electrodes orfamilies of electrodes and electrode support assemblies.

[0033] Referring now to FIG. 2A, an ITCS system 200 is illustratedincluding a can 250 with a lead 240 inserted into a dissection path 220.The lead 240 includes an electrode 230, here illustrated at the distalend of the lead 240. The dissection path 220 lies within thesubcutaneous tissue of a patient as illustrated in FIGS. 1A and 1B.

[0034] Referring to FIG. 2B, a can electrode 502 is positioned on ahousing 501 that encloses the ITCS device electronics. In oneembodiment, the can electrode 502 includes the entirety of the externalsurface of housing 501. In other embodiments, various portions of thehousing 501 may be electrically isolated from the can electrode 502 orfrom tissue. For example, the active area of the can electrode 502 mayinclude all or a portion of either the anterior or posterior surface ofthe housing 501 to direct current flow in a manner advantageous forcardiac sensing and/or stimulation.

[0035] The housing 501 may resemble that of a conventional implantableICD, and may be approximately 20-100 cc in volume, with a thickness of0.4 to 2 cm and with a surface area on each face of approximately 30 to100 cm². As previously discussed, portions of the housing may beelectrically isolated from tissue to optimally direct current flow. Forexample, portions of the housing 501 may be covered with anon-conductive, or otherwise electrically resistive, material to directcurrent flow. Suitable non-conductive material coatings include coatingsformed from silicone rubber, polyurethane, polyvinylidene fluoride, orparylene, for example.

[0036] In addition, or alternatively, all or portions of the housing 501may be treated to change the electrical conductivity characteristicsthereof for purposes of optimally directing current flow. Various knowntechniques can be employed to modify the surface conductivitycharacteristics of the housing 501, such as by increasing or decreasingsurface conductivity, to optimize current flow. Such techniques mayinclude mechanically or chemically altering the surface of the housing501 to achieve desired electrical conductivity characteristics.

[0037] In the configuration shown in FIG. 2B, the ITCS device housing501 containing the electronics (i.e., the can) is not used as anelectrode. In this case, an electrode system comprising two electrodesubsystems 508, 509 coupled to the housing 501 may be implantedsubcutaneously in the chest region of the body, such as in the anteriorthorax. The first and the second electrode subsystems 508, 509 areplaced in opposition with respect to the ventricles of a heart 510, withthe majority of the ventricular tissue of the heart 510 included withina volume defined between the electrode subsystems 508, 509. Asillustrated in FIG. 2B, the first electrode system 508 is positionedsuperior to the heart 510 relative to a superior aspect of the heart510, e.g., parallel to the left ventricular free wall. The secondelectrode system 509 is located inferior to the heart 510 and positionedin relation to an inferior aspect of the heart 510, e.g., parallel tothe right ventricular free wall. A cable or wiring 506 conductivelycouples the electrode subsystems 508, 509 to the housing 501.

[0038] In this configuration, the first and the second electrodesubsystems 508 and 509 may include any combination of electrodes usedfor sensing and/or electrical stimulation. In various configurations,the electrode subsystems 508, 509 may each include a single electrode ora combination of electrodes. The electrode or electrodes in the firstand second electrode subsystems 508, 509 may include any combination ofone or more coil electrodes, tip electrodes, ring electrodes,multi-element coils, spiral coils, spiral coils mounted onnon-conductive backing, and screen patch electrodes, for example.

[0039] The lead 240, shown in FIG. 2A, and/or the electrode subsystems508, 509, shown in FIG. 2B, may be inserted into the dissection path 220(FIG. 2A) without use of an introducer sheath, or may alternatively beinserted with use of a sheath 320 as illustrated in FIG. 3. In FIG. 3,the lead 240 extends from the sheath 320, with the electrode 230enclosed within the lumen of the sheath 320. The electrode 230 isillustrated with pharmacological agents 232 and 234 at the distal endand proximal end respectively.

[0040] Still referring to FIG. 3, the pharmacological agents 232 and 234may be incorporated with the lead 240 via, for example, a collar, aporous region, a coating, or other suitable arrangement. The lead 240may be inserted into the dissection path 220 (FIG. 2A) inside the sheath320. After proper location within the subcutaneous tissue, the sheath320 may be stripped away from the electrode 230, revealing thepharmacological agents 232 and 234 to the surrounding tissue. A periodof pharmacological activity may be initiated by impellingpharmacological agents 232 and 234 into the tissue surrounding the lead240 using phoresis such as, in the example illustrated in FIG. 3,electrophoresis.

[0041] Two non-limiting examples of phoresis are electrophoresis andsonophoresis. Electrophoresis is generally understood as anelectrochemical process in which colloidal particles and/ormacromolecules with a net electric charge migrate under the influence ofan electric potential. For purposes herein, electrophoresis issynonymous with ionophoresis, iontophoresis, and dielectrolysis.

[0042] Sonophoresis is generally understood as a sonochemical process inwhich colloidal particles and/or macromolecules migrate under theinfluence of pressure waves, such as continuous wave or burst-modeultrasound. For purposes herein, sonophoresis is synonymous withsontophoresis. Phoresis based technologies such as, for example,electrophoresis and sonophoresis, may be used in accordance with thepresent invention to impel pharmacological agents into tissue.

[0043] A non-limiting, non-exhaustive list of suitable pharmacologicalagents 232 and 234 includes analgesics, anesthetics, antibiotics,antiseptics, steroids, anti-inflammatory drugs, agents that promotehemostasis, agents that provide vasoconstriction, collagen, and agentsthat increase the rate of healing. A non-exhaustive, non-limiting listof pharmacological activities includes: antisepsis, antibiosis,analgesia, anesthesia, vasoconstriction, and hemostasis.

[0044] Suitable analgesics or anesthetics may be, for example, aspirin,IBUPROFEN, BUPIVACAINE, LIDOCAINE, MAPRIVACAINE and PROCAINE. Suitablesteroids may be, for example, DEXAMETHASONE and BETAMETHASONE. Asuitable pharmacological agent that provides vasoconstriction may be,for example, EPINEPHRINE. Suitable antibiotics or antiseptics may be,for example, VANCOMYCIN and CEFALOZIN. A suitable pharmacological agentto increase the rate of healing may be, for example, stomach submucosaderived tissue, such as that disclosed in U.S. Pat. No. 6,099,567 andincorporated herein by reference, which may be impregnated with one ormore pharmacological agents.

[0045]FIG. 4 illustrates the lead 240 with an electrode 230 and acoating 420. The coating 420 contains the pharmacological agent desirednear the distal end of the lead 240. The coating 420 may be placed onthe lead 240 by, for example, painting, spraying, dipping, vapordeposition, or other suitable arrangement. Pharmacological agents in thecoating 420 may be impelled using electrophoresis, as described earlier.

[0046]FIG. 5A illustrates a method for phoresis delivery of apharmacological agent from a system 312 without using the can's powersource, thereby conserving energy stored in the energy source disposedin the can 250. In the embodiment shown in FIG. 5A, the can 250incorporates a pharmacological agent delivery arrangement 930 disposedon the can 250. The embodiment of FIG. 5A is further shown to include atiered pharmacological delivery arrangement 950 disposed on theelectrode 230.

[0047] The arrangement 930 may partially or completely cover or coat thecan 250. For example, the arrangement 930 may cover the entire firstsurface of the can 250, but only cover 25% of a second surface toprovide a large uncoated area of the second surface to act as an activeelectrode for cardiac stimulation therapy. The second surface of the can250 may be positioned relative to the heart to optimize energy deliveryand directivity. The pharmacological delivery arrangements 930 and 950may be placed by, for example, painting, spraying, dipping, vapordeposition, or other suitable approach. The pharmacological deliveryarrangements 930, 950 may include any combination of pharmacologicalactivities or agents such as, for example, pharmacological activitiesand agents described previously.

[0048] In another configuration, the can 250 may be equipped with areservoir (seen as element 930 disposed on the can 250) within which apharmacological agent or agents can be stored. The reservoir 930 mayinclude a single chamber or multiple chambers for storing one or morepharmacological agents or other fluid useful for facilitating phoresisdelivery of a pharmacological agent. The reservoir 930 of the can 250may be fluidly connected to a surface of the can 250 in a configurationin which phoresis delivery of a pharmacological agent is implementedusing the can 250. An exit port on the surface of the can 250, throughwhich the pharmacological agent passes, may be treated or coated toenhance delivery of the pharmacological agent from the surface of thecan 250.

[0049] Alternatively, or in addition, the reservoir 930 of the can 250may be fluidly connected to the electrode 230 via a lumen of the lead240. In this configuration, a pharmacological agent may be transportedfrom the reservoir 930 of the can 250 to the electrode via the lumen tofacilitate phoresis delivery of a pharmacological agent from theelectrode 250. A micro-pump or other pressure generating arrangement maybe employed in accordance with this configuration to facilitatetransport of the pharmacological agent through the lumen of the lead240.

[0050] During and/or after the implantation process, an external driver314 may be attached to the system 312. The external driver 314 providespower and control of the phoretic impelling of the pharmacological agentduring the implantation process. The external driver 314 may beincorporated into a dissection device, so that phoresis may beaccomplished during the dissection and implantation of the system.

[0051] One approach to delivering pharmacological agents using externaldriver 314 employs the existing electrodes and wiring of the ITCS systemfor phoresis delivery. For example, the external driver 314 may use thecan 250 as a ground, grounding the patient, and may use the electrode230 to initiate an electric potential between the electrode 230 and thegrounded tissue, and impelling the pharmacological agent from thedelivery arrangement 950 using electrophoresis. In this approach, theexternal driver 314 may be simply an external power supply, such that nopower is used from the implantable components for phoresis during oracutely after implantation.

[0052] In another embodiment, the external driver 314 may be grounded tothe patient using a ground pad, such as ground pads used forelectrosurgery. In this arrangement, both the lead 240, includingelectrode 230, and the can 250 may be used as potential sources forphoresis. The external driver 314 may include a power supply as well asdriving electronics.

[0053] Referring now to FIG. 5B, an embodiment of the present inventionprovides for sonophoresis using the delivery arrangement 930. In FIG.5B, delivery arrangement 930 may be, for example, a layer ofpolyvinylidene fluoride, designated PVDF layer 934. The PVDF layer 934is a piezoelectric polymer, where applying an electric field across thepolymer causes the polymer to expand or contract, based on polarity ofthe electric potential.

[0054] The PVDF layer 934 may have a conducting surface coating 936 thatacts as a capacitor plate, storing electric charge to create an electricfield across the PVDF layer 934. Illustrated in the side view of FIG.5B, a housing 251 of the can 250 (seen in FIG. 5A) may act as a groundelectrode, and the conducting surface coating 936 may act as a sourceelectrode. A wire 932 may provide the electrical potential to theconducting surface coating 936. A pharmacological agent 938 may bedisposed on the exterior surface of the conducting surface coating 936.

[0055] Applying an electric field, such as by use of conducting surfacecoating 936 on the PVDF layer 934, creates an ultrasonic transducer. ThePVDF layer 934 of delivery arrangement 930 may be used to generate anacoustic field that impels pharmacological agents using sonophoresis.The conducting surface coating 936 may also be useful as an electrodefor driving the pharmacological agent 938 using electrophoresis.

[0056] An alternating current (AC) signal may be applied to theconducting surface coating 936 using wire 932. The AC signal creates analternating electric field across the PVDF layer 934, causing the PVDFlayer 934 to expand and contract, producing an ultrasonic field capableof driving the pharmacological agent 938 using sonophoresis. A directcurrent (DC) signal may additionally, or alternately, be applied to theconducting surface coating 936 using wire 932. The DC signal may createan electric field in the tissue capable of driving the pharmacologicalagent 938 using electrophoresis. Electrophoresis and sonophoresis mayoccur simultaneously, individually, or alternatingly as desired.

[0057] For example, it may be beneficial to phoretically impel ananalgesic in coordination with a defibrillation therapy during theentire useful life of the system 312 (FIG. 5A), to mitigate some of thediscomfort from the therapy. The delivery arrangement 930 may beactivated by the defibrillation therapy itself, or may be activatedindependently before, during, or after any therapy delivery. The therapyitself may impel the analgesic using electrophoresis and/or the deliveryarrangement 930 may impel the analgesic using sonophoresis. Illustratedhere, and as described also in previous embodiments, combinations ofpharmacological activity provided with ITCS devices may providesignificantly improved outcomes, less morbidity, and improved patientcomfort and acceptance.

[0058] Additional details of dissection devices for implantation ofsubcutaneous systems and implantable devices that may be employed oradapted to drive phoretic systems or provide phoresis are disclosed incommonly owned U.S. patent application Ser. No. 10/625,826 filed Jul.23, 2003 and entitled “TUNNELING TOOL WITH SUBCUTANEOUS TRANSDERMALILLUMINATION;” Ser. No. 10/625,833, filed Jul. 23, 2003, and entitled“SUBCUTANEOUS DISSECTION TOOL INCORPORATING PHARMACOLOGICAL AGENTDELIVERY;” Ser. No. 10/703,410, filed Nov. 7, 2003 and entitled“SUBCUTANEOUS ELECTRODE AND LEAD WITH TEMPORARY PHARMACOLOGICAL AGENTS;”and Ser. No. 10/653,456, filed Sep. 2, 2003 and entitled “ULTRASONICSUBCUTANEOUS DISSECTION TOOL INCORPORATING FLUID DELIVERY;” which arehereby incorporated herein by reference.

[0059]FIG. 6 illustrates another embodiment of the present invention. InFIG. 6, the lead 240 is shown to have a groove 610 providing a fixationpoint for a collar 620. Collar 620 may be, for example, a siliconecollar impregnated with a pharmacological agent. Collars impregnatedwith pharmacological agents are known in the art such as, for example,collars described in U.S. Pat. No. 6,361,780 hereby incorporated hereinby reference. Although the width of groove 610 is illustrated in FIG. 6to be significantly larger than the width of the collar 620, anydesirable fit may be provided.

[0060] In FIG. 6, a potential surface 614 is located beneath the collar620. The potential surface 614 may be an electrical conductor to providea source of electrical potential for electrophoresis, and/or may be asource for other forms of phoresis such as, for example, an ultrasonictransducer for sonophoresis as described above.

[0061] Referring now to FIG. 7, a three layer tiered pharmacologicaldelivery method is illustrated. The lead 240 is illustrated having afirst layer 810, a second layer 820, and a third layer 830 on the lead240. The lead 240 is further shown to include a pair of conductors 812,814 coupled to a phoretic element 800, such as a PVDF layer or otherphoresis delivery arrangement. The conductors 812, 814 may be coupled tocontacts or conductors of a driver or power source, such as driver/powersource 314 shown in FIG. 5A, for example.

[0062] The layers 810, 820, and 830 are configured such that thepharmacological agent in the third layer 830 is delivered first as thethird layer 830 is impelled away and the pharmacological agent deliversits activity. After the third layer 830 is effectively removed, thesecond layer 820 is revealed. The pharmacological agent in the secondlayer 820 is delivered second as the second layer 820 is impelled awayand the pharmacological agent delivers its activity. After the secondlayer 820 is effectively removed, the first layer 810 is revealed. Thepharmacological agent in the first layer 810 is delivered last as thefirst layer 810 is impelled away and the pharmacological agent deliversits activity. The layers 810, 820, and 830 may, for example, becontinuously or discretely applied at one or more locations along thelength of the lead 240. One or more drugs may be disposed within each ofthe layers 810, 820 and 830.

[0063]FIG. 8 illustrates an embodiment of the present invention thatdiffers from FIG. 6 by the addition of a coating 920 applied over theelectrode 230. It may be advantageous to provide a pharmacologicaldelivery to the area of tissue surrounding the electrode 230 of thesubcutaneous lead 240. For example, the electrode coating 920 mayinclude an analgesic that is adapted to be quickly delivered from theelectrode 230 using phoresis. This approach provides for an acutereduction in post-operative pain, while not hindering the electricalcapabilities of the electrode 230 for use soon after the lead 240 isplaced into the dissected tissue. The electrode coating 920 may be usedas the only pharmacological delivery arrangement, and/or may be used incombination with other pharmacological delivery arrangements such as thecollar 620 illustrated in FIG. 8 and/or the delivery arrangementsillustrated in FIG. 7 or other arrangements disclosed herein.

[0064] Various modifications and additions can be made to the preferredembodiments discussed hereinabove without departing from the scope ofthe present invention. Accordingly, the scope of the present inventionshould not be limited by the particular embodiments described above, butshould be defined only by the claims set forth below and equivalentsthereof.

What is claimed is:
 1. An implantable cardiac lead, comprising: a leadbody; an electrode supported by the lead body, the electrode configuredfor subcutaneous non-intrathoracic placement within a patient; and adriving arrangement coupled to the lead, the driving arrangementconfigured to provide phoresis delivery of a pharmacological agent fromthe lead to subcutaneous tissue.
 2. The lead according to claim 1,wherein the driving arrangement comprises the electrode supported by thelead body, the electrode configured for one or both of cardiacmonitoring and stimulation.
 3. The lead according to claim 1, whereinthe driving arrangement comprises a transducer adapted to providesonophoresis.
 4. The lead according to claim 1, wherein the electrode isconfigured as an electrode array, and the driving arrangement comprisesthe electrode array.
 5. The lead according to claim 1, wherein thedriving arrangement comprises a conductor adapted to provideelectrophoresis.
 6. The lead according to claim 1, wherein thepharmacological agent provides therapeutic treatment localized to anarea substantially surrounding at least a portion of a subcutaneousdissection path.
 7. The lead according to claim 1, wherein thepharmacological agent is provided at a plurality of locations on thelead body.
 8. The lead according to claim 1, wherein the pharmacologicalagent is impregnated into a membrane provided on the lead.
 9. The leadaccording to claim 1, wherein the lead further comprises a collar, thepharmacological agent provided at the collar.
 10. The lead according toclaim 1, wherein the lead further comprises a polymeric structure, thepharmacological agent infused within the polymeric structure.
 11. Thelead according to claim 1, wherein the lead further comprises a porousregion, the pharmacological agent at least partially filling pores ofthe porous region.
 12. The lead according to claim 11, wherein theporous region comprises a doped polymer matrix.
 13. The lead accordingto claim 1, wherein the pharmacological agent is disposed in a coatingon the lead.
 14. The lead according to claim 1, wherein thepharmacological agent comprises an analgesic or an anesthetic.
 15. Thelead according to claim 1, wherein the pharmacological agent comprisesan antibiotic or an antiseptic.
 16. The lead according to claim 1,wherein the pharmacological agent comprises a steroid or ananti-inflammatory agent.
 17. The lead according to claim 1, wherein thepharmacological agent comprises an agent that promotes hemostasis orprovides vasoconstriction.
 18. An implantable system, comprising: alead, comprising: a lead body; and an electrode coupled to the leadbody, the electrode configured for subcutaneous non-intrathoracicplacement within a patient; and a can coupled to the lead, the canconfigured to provide phoresis delivery of a pharmacological agent fromat least a portion of the can to subcutaneous tissue.
 19. The systemaccording to claim 18, wherein the can is configured to provideelectrophoresis.
 20. The system according to claim 18, wherein the canis configured to provide sonophoresis.
 21. The system according to claim18, further comprising a driving arrangement provided on the lead andconfigured to provide phoresis delivery of a pharmacological agent fromat least a portion of the lead to the subcutaneous tissue.
 22. Thesystem according to claim 18, wherein the lead and the can areconfigured to produce an electric potential between the lead and thecan, the electric potential produced to provide the phoresis delivery ofthe pharmacological agent.
 23. The system according to claim 18, whereinthe pharmacological agent is impregnated into a membrane provided on thecan.
 24. The system according to claim 18, wherein the can comprises areservoir fluidly coupled to a port defined on the portion of the can,the reservoir comprising one or more chambers for storing one or morepharmacological agents.
 25. The system according to claim 18, whereinthe can comprises a porous region, the pharmacological agent at leastpartially filling pores of the porous region.
 26. The system accordingto claim 25, wherein the porous region comprises a doped polymer matrix.27. The system according to claim 18, wherein the pharmacological agentis disposed in a coating on the can.
 28. The system according to claim27, wherein the coating covers at least 25% of a surface area of thecan.
 29. The system according to claim 18, wherein the pharmacologicalagent comprises an analgesic or an anesthetic.
 30. The system accordingto claim 18, wherein the pharmacological agent comprises an antibioticor an antiseptic.
 31. The system according to claim 18, wherein thepharmacological agent comprises a steroid or an anti-inflammatory agent.32. The system according to claim 18, wherein the pharmacological agentcomprises an agent that promotes hemostasis or providesvasoconstriction.
 33. A method of lead implantation, comprising:delivering a lead into subcutaneous non-intrathoracic tissue of apatient, the lead comprising a lead body, an electrode, and apharmacological agent on the lead; and impelling, using phoresis, thepharmacological agent from at least a portion of the lead to thesubcutaneous non-intrathoracic tissue.
 34. The method according to claim33, wherein impelling the pharmacological agent comprises generating anelectric field for impelling the pharmacological agent usingelectrophoresis.
 35. The method according to claim 33, wherein impellingthe pharmacological agent comprises generating ultrasonic waves forimpelling the pharmacological agent ultrasonically.
 36. The methodaccording to claim 33, wherein impelling the pharmacological agent usingphoresis comprises impelling a plurality of pharmacological agents. 37.The method according to claim 33, wherein impelling the pharmacologicalagent comprises impelling a first pharmacological agent usingelectrophoresis and impelling a second pharmacological agent usingsonophoresis.
 38. The method according to claim 33, further comprisingdelivering a can into subcutaneous non-intrathoracic tissue of thepatient, the can comprising an electrode or an electrically conductiveregion, and a pharmacological agent; and impelling, using phoresis, thepharmacological agent from at least a portion of the can to thesubcutaneous non-intrathoracic tissue.
 39. The method according to claim38, wherein impelling the pharmacological agent from the can comprisesgenerating an electric field for impelling the pharmacological agentfrom the can using electrophoresis.
 40. The method according to claim38, wherein impelling the pharmacological agent comprises generatingultrasonic waves for impelling the pharmacological agent ultrasonicallyfrom the can.
 41. The method according to claim 38, wherein impellingthe pharmacological agent from the can using phoresis comprisesimpelling a plurality of pharmacological agents from the can.
 42. Themethod according to claim 38, wherein impelling the pharmacologicalagent from the can comprises impelling a first pharmacological agentusing electrophoresis and impelling a second pharmacological agent usingsonophoresis.
 43. The method according to claim 33, further comprising:providing a removable sheath having a lumen; advancing the lead throughthe lumen to an implant location; and removing the sheath from the leadwith the lead remaining at the implant location.
 44. The methodaccording to claim 33, wherein the pharmacological agent comprises ananalgesic or an anesthetic.
 45. The method according to claim 33,wherein the pharmacological agent comprises an antibiotic or anantiseptic.
 46. The method according to claim 33, wherein thepharmacological agent comprises a steroid or an anti-inflammatory agent.47. The method according to claim 33, wherein the pharmacological agentcomprises an agent that promotes hemostasis or providesvasoconstriction.
 48. An implantable cardiac lead, comprising: a leadbody; an electrode coupled to the lead body, the electrode configuredfor subcutaneous non-intrathoracic placement in a patient; and means,coupled to the implantable lead, for impelling a pharmacological agentusing phoresis into subcutaneous non-intrathoracic tissue.
 49. The leadaccording to claim 48, wherein the impelling means comprises means forimpelling the pharmacological agent using electrophoresis.
 50. The leadaccording to claim 48, wherein the impelling means comprises means forimpelling the pharmacological agent using sonophoresis.
 51. The leadaccording to claim 48, wherein the pharmacological agent comprises ananalgesic or an anesthetic.
 52. The lead according to claim 48, whereinthe pharmacological agent comprises an antibiotic or an antiseptic. 53.The lead according to claim 48, wherein the pharmacological agentcomprises a steroid or an anti-inflammatory agent.
 54. The leadaccording to claim 48, wherein the pharmacological agent comprises anagent that promotes hemostasis or provides vasoconstriction.
 55. Asystem, comprising: an implantable medical device, comprising: a canthat houses circuitry configured to provide one or both of cardiacmonitoring and cardiac stimulation; and a lead coupled to the can, thelead comprising a lead body and an electrode coupled to the lead body,the electrode configured for subcutaneous non-intrathoracic placementwithin a patient; and a driver apparatus detachably coupled to theimplantable medical device, the driver apparatus configured tofacilitate phoresis delivery of a pharmacological agent from one or bothof the can and the lead.
 56. The system according to claim 55, whereinthe driver apparatus facilitates electrophoresis delivery of thepharmacological agent.
 57. The system according to claim 55, wherein thedriver apparatus facilitates sonophoresis delivery of thepharmacological agent.
 58. The system according to claim 55, wherein thelead and the can are configured to produce an electric potential betweenthe lead and the can to provide the phoresis delivery of thepharmacological agent.
 59. The system according to claim 55, wherein thedriver is configured to provide a phoresis power signal to theimplantable medical device.
 60. The system according to claim 59,wherein the phoresis power signal is a DC voltage.
 61. The systemaccording to claim 59, wherein the phoresis power signal is an AC signalalternating at an ultrasonic frequency.
 62. The system according toclaim 59, wherein the phoresis power signal is a DC bias voltage with anAC signal alternating at an ultrasonic frequency.
 63. The systemaccording to claim 55, wherein the pharmacological agent comprises ananalgesic or an anesthetic.
 64. The system according to claim 55,wherein the pharmacological agent comprises an antibiotic or anantiseptic.
 65. The system according to claim 55, wherein thepharmacological agent comprises a steroid or an anti-inflammatory agent.66. The system according to claim 55, wherein the pharmacological agentcomprises an agent that promotes hemostasis or providesvasoconstriction.